Process of extracting metals from minerals, rocks, and other materials.



the residues and said gases are then further treated together with thenitrous gases. The acid contained in the residues is hereby completelyutilized. rlhe gases obtained by the roasting of the ore before leachingand which contain sulfur 'dioxid are suitably mixed in a hot state Withoxidized nitrous gases from the air combustion furnaces, an

Aexcess of said gases being preferably used in order that no nitrogenoxid may be lost. The nitrogen dioxid (NO2) contained in these oxidizedgases Will oxidize the sulfurous acid into sulfuric acid anhydrid, whichisv then extracted. Supposing that the air used for the roasting and aircombustion operations has been well dried, a cornp'ound of sulfurousacid and nitrogen oxid will be formed, which compound may afterwardreadily be decomposed so that the sulfuric acid and the nitrogencompound may be separated and then extracted. The lower nitrogen oxygencompounds obtained by the oxidation of the sulfurous acid are suit-ablyreoxidized and further worked in the ordinary way. The extraction oftheore with nitric acid may also be effected without a previous roasting ofthe ore, extracting direct-ly with warm acid. The gases thereby .formedare introduced into the absorption towers. For keeping Warm the acidemployed hot furnace gases may suitably be used. X'Vhen working in thismanner a separation of sulfur and a formation of gaseous compounds ofsulfur will take place simultaneously with the dissolut-ion of themetals. The free and bound sulfur thus obtained is utilized in themanner that ,the gases formed by the reaction are returned to the acidtower, while the sulfur obtained in an elementary condition may beseparated from the solution Ain suitable filtering apparatus. AfterWashing and purifying this sulfur will form a valuable commercialarticle. The metal salt-solution may then above described be furtherworked. Under certain circumstances it may also be of advantage to treatthe ore with highly heated steam prior to the extract-ion, to expel inthis mannera larger or smaller portion of the sulfur.

When using, the process for treating ores containing zinc and` copper,said metals may be separated from each other by dissolving the zinc withdilute, warm (not boiling hot) nitric acid, the copper remainingundissolved Instead of completely neutralizing the so lution obtained bythe extraction, in the manner above described with limeior soda, it maysometimes be of advantage to treat the solution (which for variousreasons may contain considerable quantities of free acid, fitter aliabecause the ore will not be dissolved by very dilute acid) withlimestone in such manner as to only nearly neutralize it. Thereby thesulfuric acid, which may have been formed in the nitric acid treatment,is precipitated in the forni of gypsum, which'may be filtered olii'. Thesolution which will now contain only nitrate, is then further treatedfor obtainin the nitrates as such or for recipitating t e metals asoxids or basic car onates using as a precipitating a ent lime, magnesia,their carbonates or t e like.Y The solution obtainedA after repeatedfiltering may then be worked for the production of nitrate of lime.

From the above description it will be seen that a decided advantageresults in treating or lixiviating any kind of -Jore or metalliferousmaterial with the intermediary products resulting from furnaces of theclass mentioned. That is, the furnace gases are conducted directly intothe ore and before they have had an opportunity to cool and change theirconstituents by mutual combination. Nitric acid treatment for ores, evenof moderately lean ores, is commercially practicable by using the gasesdirect from the furnaces, for the nit-rifaction of air. The heat ofthese gases -is not wasted, the water used for washing the treated orebeing employed for the absorption of further quantities of nitrous gasesin treating new quantities of material, and the acid left in the ore isevaporated by means of the hot gases. f

Claims:

l. The process of treating ores containing sulfur, which comprisesroasting t-he` ore with hot nitrogen oxid gases, lwithdrawing the gasesevolved and mixing them with further quantities of nitrogen oxid gases,absorbing the mixed gases inwater to form a weak acid solution, treatingthe roasted4 ore with said acid solution, withdrawing the Isolution andrecovering values dissolved from the cre.

2. The process of treat-ing ores containing sulfur, which comprisesroasting the ore .with hot nitrogen oxid gases, withdrawing the gasesevolved and mixing them with further quantities of nitrogen oxid gases,absorbing the mixed gases in water to form a weak acid solution,treating the roasted ore with said acid solution, forcing hot nitroge/nvoxid gases through the residue to eliminate any nit-ric acid, absorbingthe res'ulting .gas to form Weak acid and recoverling values dissolvedfrom the ore.

In testimony that I claim the foregoing as my invention, I have signedmy name in presence of two subscribin witnesses.

, KRISTIAN IRKELAND. Witnesses:

' M. E. Gnrsonimsen,

RUTH Ianns'rnx.

